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PostPosted: Thu Feb 02, 2006 7:49 pm 
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Joined: Wed Jan 18, 2006 6:33 pm
Posts: 96
I have an Asus A8N-VM CSM motherboard with integrated SPDIF. The audio is driven my an AD1986a chip which uses the snd-hda-intel alsa driver.

I can get knoppmyth to output PCM stereo audio over the SPDIF cable, but I can't get AC3 pass though to work. Hence playing DVDs just results in Stereo audio.

Has anyone got AC3 to work with this chipset.

At the moment i'm using alsa-driver-1.0.11rc2 with a couple of patches to fix the annoying buzz you get with a 2ch stereo signal. I don't know the alsa code well enough to know if this has broken the digital support.

I've also tried a couple of variants on a .asoundrc which haven't made a difference.

Any tips/pointers.

Steve


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PostPosted: Sun Feb 19, 2006 6:47 pm 
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Joined: Wed Jan 18, 2006 6:33 pm
Posts: 96
Ok i've managed to get spdif ac3 passthroug working finally. Just needed the correct settings in mplayer.

my ~mythtv/.mplayer/config contains

Code:
ao=alsa:device=digital
ac=hwac3,


This means that none ac3 avi files play over the spdif as PCM audio, and any DVDs or AVI files with AC3 do pure passthrough.

Steve


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PostPosted: Sat Jun 10, 2006 2:37 pm 
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Joined: Tue Mar 28, 2006 8:26 pm
Posts: 804
Location: Minneapolis, MN
I see your config file additions are only to get AC3 passthrough going. I'm still trying to get basic stereo digital audio out.

A friend and I have the same Asus motherboard. My friend just started trying to get digital audio off the coaxial SPDIF output. He's running it into a new Yamaha home theater receiver - no audio - not even stereo.

Is there a BIOS setting that needs to get turned on?
Are there Mythtv settings that need to be turned on?

Eric

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KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner


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PostPosted: Mon Jun 12, 2006 12:39 am 
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Joined: Wed Jan 18, 2006 6:33 pm
Posts: 96
Ok you need to setup a .asoundrc for the mythtv user that does all of the correct audio routing.

Copy the enclosed to .asoundrc and you should be able to route both PCM and AC3 via your digital out.

Code:
# Override the default output used by ALSA.
# If you do not override the default, your default
# device is identical to the (unmixed) analog device
# shown below.  If you prefer mixed and/or digital
# output, uncomment the appropriate four lines below
# (only one slave.pcm line).
pcm.!default {
  type plug
## Uncomment the following to use mixed analog by default
#  slave.pcm "dmix-analog"
## Uncomment the following to use unmixed digital by default
#  slave.pcm "digital-hw"
## Uncomment the following to use mixed digital by default
#  slave.pcm "dmix-digital"
## Uncomment the following to use analog & digital at same time by default
   slave.pcm "anadig-hw"
#   slave.pcm "anadig-hw8"
}

# Alias for analog output on the nForce2/4 (hw:0,0)
# - This is identical to the device named "default"--which
# always exists and refers to hw:0,0 (unless overridden)
# - Therefore, we can specify "hw:0,0", "default", or "analog"
# to access analog output on the nForce2/4
pcm.analog {
 type plug
 slave.pcm "analog-hw"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.analog {
 type hw
 card 0
}

# Alias for (rate-converted) mixed analog output on the
# nForce2 (hw:0,0)
#  - This will accept audio input--regardless of rate--and
# convert to the rate required for the dmix plugin
# (in this case 48000Hz)
pcm.mixed-analog {
 type plug
 slave.pcm "dmix-analog"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.mixed-analog {
 type hw
 card 0
}

# Alias for (rate-converted) digital (S/PDIF) output on the
# nForce2 (hw:0,1)
#  - This will accept audio input--regardless of rate--and
# convert to the rate required for the S/PDIF hardware
# (in this case 48000Hz)
pcm.digital {
 type plug
 slave.pcm "digital-hw"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.digital {
 type hw
 card 0
}

# Alias for mixed (rate-converted) digital (S/PDIF) output on the
# nForce2/4 (hw:0,1)
#  - This will accept audio input--regardless of rate--and
# convert to the rate required for the S/PDIF hardware
# (in this case 48000Hz)
pcm.mixed-digital {
 type plug
 slave.pcm "dmix-digital"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.mixed-digital {
 type hw
 card 0
}

# The following devices are not useful by themselves.  They
# require specific rates, channels, and formats.  Therefore,
# you probably do not want to use them directly.  Instead use
# of of the devices defined above.

# Alias for analog output on the nForce2 (hw:0,0)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.analog-hw {
 type hw
 card 0
 # The default value for device is 0, so no need to specify
}

# Control device (mixer, etc.) for the nForce2/4 card
ctl.analog-hw {
 type hw
 card 0
}
# Alias for (rate-converted) digital (S/PDIF) output on the
# nForce2 (hw:0,1)
#  - This will accept audio input--regardless of rate--and
# convert to the rate required for the S/PDIF hardware
# (in this case 48000Hz)
pcm.digital {
 type plug
 slave.pcm "digital-hw"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.digital {
 type hw
 card 0
}

# Alias for mixed (rate-converted) digital (S/PDIF) output on the
# nForce2/4 (hw:0,1)
#  - This will accept audio input--regardless of rate--and
# convert to the rate required for the S/PDIF hardware
# (in this case 48000Hz)
pcm.mixed-digital {
 type plug
 slave.pcm "dmix-digital"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.mixed-digital {
 type hw
 card 0
}

# The following devices are not useful by themselves.  They
# require specific rates, channels, and formats.  Therefore,
# you probably do not want to use them directly.  Instead use
# of of the devices defined above.

# Alias for analog output on the nForce2 (hw:0,0)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.analog-hw {
 type hw
 card 0
 # The default value for device is 0, so no need to specify
}

# Control device (mixer, etc.) for the nForce2/4 card
ctl.analog-hw {
 type hw
 card 0
}
# Alias for digital (S/PDIF) output on the nForce2/4 (hw:0,1)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.digital-hw {
 type hw
 card 0
 device 1
}

# Control device (mixer, etc.) for the nForce2/4 card
ctl.digital-hw {
 type hw
 card 0
}

# Direct software mixing plugin for analog output on
# the nForce2/4 (hw:0,0)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.dmix-analog {
 type dmix
 ipc_key 1234
 slave {
   pcm "analog-hw"
   period_time 0
   period_size 1024
   buffer_size 4096
   rate 48000
 }
}

# Control device (mixer, etc.) for the nForce2/4 card
ctl.dmix-analog {
 type hw
 card 0
}

# Direct software mixing plugin for digital (S/PDIF) output
# on the nForce2/4 (hw:0,1)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.dmix-digital {
 type dmix
 ipc_key 1235
 slave {
   pcm "digital-hw"
   period_time 0
   period_size 1024
   buffer_size 4096
   rate 48000
}

# Control device (mixer, etc.) for the nForce2/4 card
ctl.dmix-digital {
 type hw
 card 0
}

###################################################
# Setup for Analog + Digital dual ouput
#
# Taken From Knoppmyth Forum Posting
# http://mysettopbox.tv/phpBB2/viewtopic.php?t=8369

# this device dups audio to both digital and analog outs (ac3 will give noise on analog outs)
# I use script so mplayer & xine only send ac3 if myth ac3 flag is on
pcm.anadig {
 type plug
 slave.pcm "anadig-hw"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.anadig {
 type hw
 card 0
}

# this one creates a four-channel output PCM device
pcm.multi-anadig {
        type multi;
        slaves.a.pcm "analog-hw"; # this is the default output
        slaves.a.channels 2;
        slaves.b.pcm "digital-hw"; # this is the SPDIF output
        slaves.b.channels 2;
        bindings.0.slave a;
        bindings.0.channel 0;
        bindings.1.slave a;
        bindings.1.channel 1;
        bindings.2.slave b;
        bindings.2.channel 0;
        bindings.3.slave b;
        bindings.3.channel 1;
}

ctl.multi-anadig {
        type hw;
        card 0;
}

# this duplicates input from 2 channels to 4 channels and
# sends the output to multi, above.
pcm.anadig-hw {
        type route;
        slave.pcm "multi-anadig";
   slave.channels 4;
        ttable.0.0 1;
        ttable.1.1 1;
        ttable.0.2 1;
        ttable.1.3 1;
}


ctl.anadig-hw {
        type hw;
        card 0;
}


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OpenMedia Limited
New Zealands first open source PVR based on Knoppmyth
http://www.openmedia.co.nz for details


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PostPosted: Mon Jun 12, 2006 3:55 pm 
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Joined: Tue Mar 28, 2006 8:26 pm
Posts: 804
Location: Minneapolis, MN
steven_ellis wrote:
Ok you need to setup a .asoundrc for the mythtv user that does all of the correct audio routing.

Copy the enclosed to .asoundrc and you should be able to route both PCM and AC3 via your digital out.


I do have the Asus SPDIF output board in my computer.

Just to clarify: if I don't make any of your audio config file additions to KnoppMyth as installed from the installer cd, should there be any sort of digital audio output from the Asus SPDIF output board? I don't have a digital ready audio amplifier *yet* but when I play back recorded tv and live tv, the optical audio output in the Asus SPDIF output board does light up red. I've currently got no way to know if there is any audio encoded on the red light. :)

Thanks for your help! That is some nice work!

Eric

_________________
KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner


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PostPosted: Tue Jun 13, 2006 12:54 am 
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Joined: Wed Jan 18, 2006 6:33 pm
Posts: 96
neutron68 wrote:
[

Just to clarify: if I don't make any of your audio config file additions to KnoppMyth as installed from the installer cd, should there be any sort of digital audio output from the Asus SPDIF output board? I don't have a digital ready audio amplifier *yet* but when I play back recorded tv and live tv, the optical audio output in the Asus SPDIF output board does light up red. I've currently got no way to know if there is any audio encoded on the red light. :)



You will get some limited audio out over spdif without an .asoundrc file. Problem is not all amps support all audio over spdif without some form of rate conversion. The enclosed .asoundrc takes care of most of that, plus I can dual route audio. Ive got an analog amp plugged into the stereo out and a digital amp into the spdif out.

Steve

_________________
OpenMedia Limited
New Zealands first open source PVR based on Knoppmyth
http://www.openmedia.co.nz for details


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PostPosted: Tue Jun 13, 2006 9:38 pm 
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Joined: Tue Mar 28, 2006 8:26 pm
Posts: 804
Location: Minneapolis, MN
I spent the evening at my friend's house. He has the same Asus motherboard as us and he gets no digital audio output out of Mythtv. I took my Asus SPDIF module over and it does not light up when plugged into his system - like it does on mine. I checked all his BIOS and Myth settings to be sure they are like mine.

6-3-06

Just last night I discovered that his iec985 setting was muted in the ALSAMIXER. After un-muting that, he has digital audio output!

Eric

_________________
KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner


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